1. Field of the Invention
The present invention generally relates to transfer control methods and information processing apparatuses, and more particularly to a transfer control method for controlling transfer of information such as data and commands with respect to a plurality of processors, and to an information processing apparatus which employs such a transfer control method.
In an information processing apparatus having a plurality of processors, the amount of data processed is extremely large. For this reason, there are demands to realize a transfer control method which can transfer data among the processors at a high speed.
2. Description of the Related Art
FIG. 1 is a system block diagram for explaining an example of a conventional transfer control method. An information processing apparatus shown in FIG. 1 generally includes a plurality of processors 1-1 through 1-n, a control block 2, and a reserve 3. The control block 2 is a kind of processor which has a buffering function and is provided for exclusive control. The reserve 3 is made up of a register which indicates a transfer status of data or command among the processors 1-1 through 1-n (transfer units). The transfer status indicates busy or free, and is used for the exclusive control of the transfer. For the sake of convenience, it is assumed that the processor 1-1 forms a request source, and the processors 1-2 through 1-n form request destinations.
When the request source processor 1-1 generates a request, the data and commands from the request source processor 1-1 are once supplied to and stored in the control block 2. Based on the stored data and commands, the control block 2 acquires the reserve 3 between the control block 2 and the request destination processor 1-2, for example, and transfers the data and commands to the request destination processor 1-2.
Accordingly, after supplying the data and commands to the control block 2, the request source processor 1-1 can carry out other processes.
However, according to the conventional transfer control method, the transfer of the data and commands from the request source processor 1-1 to the request destination processor 1-2 is made asynchronously, and there was a problem in that a synchronous transfer of the data and commands cannot be made.
In addition, in a case where the request source processor 1-1 successively generates requests, it is necessary to acquire the reserve 3 each time the request is generated, and there was another problem in that the transfer efficiency is poor.
Accordingly, it is a general object of the present invention to provide a novel and useful transfer control method and information processing apparatus, in which the problems described above are eliminated.
Another and more specific object of the present invention is to provide a transfer control method and information processing apparatus, which can make synchronous transfer and asynchronous transfer of data and commands, and also improve the transfer efficiency.
Still another object of the present invention is to provide a transfer control method comprising a selecting step which selects one of a first route for making an asynchronous transfer to a request destination via a control block and a second route for making a synchronous transfer to the request destination by not passing the control block, with respect to a request from a request source. According to the transfer control method of the present invention, it is possible to realize synchronous transfer and asynchronous transfer of data and commands, and also improve the transfer efficiency.
A further object of the present invention is to provide an information processing apparatus comprising a control block at least having a buffering function, and a selector selecting one of a first route for making an asynchronous transfer to a request destination via the control block and a second route for making a synchronous transfer to the request destination by not passing the control block, with respect to a request from a request source. According to the information processing apparatus of the present invention, it is possible to realize synchronous transfer and asynchronous transfer of data and commands, and also improve the transfer efficiency.